JP4730159B2 - Sliding member and manufacturing method thereof - Google Patents

Description

The present invention, unlubricated condition and under water, organic solvents, fuels, are used under an oil lubricated environment, relates to a sliding member and a manufacturing method thereof having a low friction hard carbon coating.

  The hard carbon coating generally has a high hardness, a smooth surface, excellent friction resistance, and excellent low friction performance with a low coefficient of friction due to its solid lubricity.

  In a non-lubricated environment, the friction coefficient of the normal smooth steel surface is 0.5 to 1.0, and the surface treatment materials such as Ni-P plating, Cr plating, TiN coating, and CrN coating, which are conventional surface treatment materials, are used. The coefficient of friction is about 0.4, whereas the coefficient of friction on the surface of the hard carbon coating is about 0.12.

  Currently, using these excellent characteristics, it is used in a non-lubricated environment such as cutting tools such as drill blades, grinding tools, etc., plastic working dies, valve cocks and capstan rollers. Application to sliding members and the like.

  On the other hand, in mechanical parts such as an internal combustion engine in which reduction of mechanical loss as much as possible is desired from the viewpoint of energy consumption and environment, sliding with lubricating oil is currently the mainstream. However, if low friction is achieved by the hard carbon coating having these solid lubricity in a non-lubricated environment, it is preferable because the load on the machine parts can be reduced even when the lubricating oil is exhausted in the sliding member, Moreover, since it becomes possible to reduce lubricating oil in the future, it is preferable for consideration of the global environment.

  Patent Document 1 describes a technique for reducing the solid lubricity of a lubricating oil by adding 5 to 70 at% of a metal element in such a hard carbon coating.

JP 2001-316686 A

  However, the technique described in Patent Document 1 does not mention a technical problem that the hard carbon film is peeled off by a load on the sliding member during sliding in a non-lubricated environment. Therefore, in the prior art, there is a problem that the friction resistance inherently possessed by the hard carbon coating in a non-lubricated environment cannot be utilized.

Then, this invention is providing the sliding member provided with the hard carbon film which can utilize the friction resistance which a hard carbon film originally has, and its manufacturing method .

The manufacturing method of the sliding member of the present invention comprises a diamond-like carbon film containing 0.5 to 4.5 at% aluminum element on a base material by an unbalanced magnetron sputtering (UBMS) method. A hard carbon film is formed, and an aluminum element exposed on the surface of the hard carbon film is reacted with oxygen and water in the atmosphere to form aluminum oxide and / or aluminum hydroxide.

  Moreover, the thickness of the hard carbon coating is 0.5 μm or more and 10.0 μm or less, and the surface roughness of the hard carbon coating is 0.1 μm or less.

The sliding member of this invention is obtained by said manufacturing method. The Young's modulus of the hard carbon film formed on the substrate is preferably 50 GPa or more and 180 GPa or less.

  On the other hand, the substrate is preferably made of an alloy containing Fe, Cr, and Mo. Furthermore, it is preferable that a Cr layer is formed on an alloy containing Fe, Cr, and Mo. Furthermore, it is preferable that a Cr / C layer in which Cr and C are mixed is formed in the Cr layer.

The hard carbon coating used here is preferably a hard carbon coating in which sp ² bonded carbon and sp ³ bonded carbon are mixed.

  The present invention can provide a hard carbon coating that can make use of the friction resistance inherently possessed by the hard carbon coating.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to the Example shown below.

  The hard carbon film shown in the present invention can be applied to sliding members such as machine parts used in a non-lubricated environment.

  A friction test was performed using a test piece 1 in which a hard carbon coating 3 was coated on a disk substrate 2 having a diameter of 21.5 mm and a thickness of 5.2 mm as shown in FIG.

  The test piece 1 at this time formed the hard carbon film 3 on the disk substrate 2 with the specifications (film treatment, film formation method, Al content, film thickness) as shown in Table 1.

As the hard carbon coating 3, a diamond-like carbon (DLC) coating was formed on the disc substrate 2 by using an unbalanced magnetron sputtering (UBMS) method.

  In the UBMS method, the balance of the magnetic poles arranged on the back side of the target is intentionally broken at the center and the peripheral part of the target, and a part of the lines of magnetic force from the magnetic poles at the peripheral part of the target is made unbalanced Extend to the substrate. Then, the plasma that has converged in the vicinity of the target is easily diffused to the vicinity of the base material along the magnetic field lines. This is a film forming method characterized in that the amount of ions irradiated onto the substrate during film formation can be increased, and as a result, a dense film can be formed on the substrate.

  After the hard carbon coating 3 was formed, the coating surface was evaluated by a nanoindentation method (ISO14577) and a friction test.

  Evaluation by the nano-indentation method (ISO14577) is performed by pushing a Belkovic triangular pyramid indenter with an opposite edge angle of 115 degrees into the surface of the hard carbon coating 3 to a maximum load of 3 mN over 10 seconds, holding the maximum load for 1 second, and then 10 seconds. It was performed under the condition of unloading.

  The indentation Young's modulus was calculated from this evaluation.

  As an evaluation apparatus for the friction test, the friction coefficient and the peeling load of the hard carbon film (in the case of Comparative Example 1, the baking load of the base material) are obtained using a ball-on-disk type wear tester 11 as shown in FIG. Measured.

  In this apparatus, a work table 13 fixed to a rotating shaft 12 is arranged, and a test piece 1 is installed on the work table 13, and a metal ball (high carbon chromium bearing steel material having a diameter of 6 mm is provided on the upper surface side of the test piece 1. , JIS SUJ2 ball) 14 is used as the counterpart material of the test piece 1. Here, the metal used for the metal ball is made of steel used for the bearing.

  In this apparatus, the load 15 is configured to increase and press the load P in a stepwise manner by 98 N per minute at a load P of 98 N to 2452 N by the spring 15.

  At this time, the metal ball 14 is fixed by the holder 16 so as not to rotate. Then, the rotating shaft 12 is connected to the motor 17 and is driven to rotate relative to the metal ball 14 at a relative sliding speed of 30 mm / sec, and a torque corresponding to the frictional force generated between the metal ball 14 and the test piece 1. Was measured with the load cell 18, and the friction coefficient was calculated.

  One metal ball 14 is disposed at a radius of 8 mm from the center as shown in FIG.

  The peeling load of the hard carbon coating 3 (in the case of Comparative Example 1, the baking load of the base material) was the test load when the friction coefficient between the test piece 1 and the metal ball 14 rapidly increased. Further, this friction test was performed in a non-lubricated state under a normal temperature and humidity environment (room temperature: about 25 ° C., humidity: about 60% RH).

  Carburization so that the hardness of the surface of the disk substrate 2 made of an alloy containing Fe, Cr, Mo (chromium molybdenum steel, JIS SCM415) is 58 or more on Rockwell C scale (HRC). The surface roughness (Ra) was finished to 0.1 μm or less by processing.

  Thereafter, while introducing an inert gas and a hydrocarbon gas, the hard carbon coating (hereinafter abbreviated as “coating”) 3 is made to have a content of 0.65 at% by the UBMS method. Membrane was performed.

Ra of the film 3 after film formation was 0.021 μm. The Young's modulus of the film 3 is 65.94.
It was GPa. Further, in the friction test between the coating 3 and the metal ball 14, the friction coefficient was 0.052, and the peeling load of the coating 3 was 2452N or more.

  When the coating in this example is slid in a non-lubricated environment, the friction coefficient is 0.1 or less, and the friction coefficient is about 87% to 95% compared to steel materials without coating or conventional surface treatment materials. Further, it was found that the friction coefficient can be reduced by about 57% compared to the conventional coating film, and furthermore, since the peeling load of the coating film is as large as 490 N or more, the low friction performance of the coating film can be utilized.

  When the coating in the present embodiment is applied to a non-lubricated sliding member of a mechanical device, the load on the mechanical device involving the sliding member can be reduced, and as a result, a mechanical device with high energy efficiency can be provided.

  In addition, since the coating film of this embodiment supports sliding in a non-lubricated environment, the reliability of the mechanical device when the lubricating oil is depleted in the sliding member of the mechanical device using the lubricating oil. On the other hand, the lubricating oil can be reduced, and as a result, an environmentally friendly mechanical device can be provided.

  Since the coating film of this example does not peel off from the substrate, the substrate is not exposed and the low friction property of the coating film can be utilized.

The film of this example is a hard carbon film in which sp ² bonded carbon, which is a carbon bond typified by graphite, and sp ³ bonded carbon, which is a carbon bond typified by diamond, are mixed.

The surface layer and the inside of this coating contain aluminum element. Its content is 0.5
At% or more and 4.5 at% or less, preferably 0.6 at% or more and 1.9 at% or less.

  The aluminum element is at least one substance selected from metallic aluminum, aluminum boride, aluminum carbide, aluminum nitride, aluminum oxide, and aluminum hydroxide, preferably aluminum oxide and / or Present as aluminum hydroxide.

  Thereby, it is possible to provide a coating film having both peeling resistance and a low friction coefficient even in a non-lubricated environment.

  The hard carbon film is a film made of amorphous carbon or hydrogenated carbon, and is called amorphous carbon, hydrogenated amorphous carbon (aC: H), diamond-like carbon (DLC), or the like.

  For its formation, plasma CVD method for forming a film by plasma decomposition of hydrocarbon gas, gas phase synthesis method such as ion beam evaporation method using carbon and hydrocarbon ions, ion for forming a film by evaporating graphite etc. by arc discharge A plating method, a sputtering method for forming a film by sputtering a target under an inert gas atmosphere, or the like is used.

  Such a coating formed by this example has low friction and can be applied to the sliding member. As a result, a sliding member that can reduce the load even in a non-lubricated environment is provided, and reliability can be maintained even when the lubricating oil is exhausted in a machine part that is normally slid in lubricating oil. It is possible to reduce the lubricating oil.

  The aluminum element exposed on the surface of the coating reacts with oxygen and water in the atmosphere to form aluminum oxide and aluminum hydroxide. It is also possible to provide a dielectric coating that is stable as a characteristic.

  Moreover, since such a film contains an aluminum element, in particular, the aluminum element on the surface of the film exists as an aluminum oxide and an aluminum hydroxide. In other words, the surface of the coating is hydrophilic, and low friction can be realized by sliding in the presence of water. Further, sliding in the presence of a liquid or vapor (for example, alcohols) having the same OH group as water. There is a merit that low friction can be realized even when moving.

  In this example, the presence of an aluminum element in the coating reduces the internal stress of the coating, and thus the phenomenon that it is difficult to peel from the substrate is found.

  When the content of the aluminum element in the coating is less than 0.5 at%, the effect of reducing friction cannot be expected because the amount of aluminum oxide and / or aluminum hydroxide derived from hydrophilicity is very small on the surface of the coating.

  On the other hand, when the content of the aluminum element on the surface of the coating or inside was about 5 at% or more, it was presumed that the progress of carbide formation of aluminum was remarkable from the result of X-ray photoelectron spectroscopy (XPS) analysis. That is, when the content of the aluminum element on the surface or inside the coating is about 5 at% or more, the amount of aluminum carbide produced is excessively increased, and the coating is liable to break due to embrittlement of the aluminum carbide.

  Further, the Young's modulus of the coating increases due to the formation of aluminum carbide, and when it exceeds 180 GPa, the coating tends to crack or peel off. Moreover, when it is less than 50 GPa, the load resistance at the time of sliding falls.

  In the aluminum element used for the coating, particularly when it is present as an aluminum oxide or aluminum hydroxide, it has a high affinity with a liquid or vapor having an OH group, so that low friction can be realized.

Further, when the thickness of the coating is less than 0.5 μm, abrasion is likely to occur due to sliding.
If it exceeds μm, the internal stress of the coating becomes large and peeling tends to occur, which is not preferable. Since the surface of the coating has high hardness, the mating material wears as the surface roughness exceeds 0.1 μm and becomes rough.

  The coating is formed by sputtering, plasma CVD, ion plating, or the like. Preferably, the coating is formed by sputtering or ion plating.

  In the case of sputtering or ion plating, aluminum can be formed into a film by sputtering an aluminum target.

  On the other hand, in plasma CVD, aluminum can be formed into a film by introducing an organic aluminum compound typified by trimethylaluminum into the chamber as a gas.

  In addition, the applications targeted by this embodiment are those requiring durability, for example, sliding parts for automobiles, in particular, refrigerant compressors and rotary compressors used in engine cylinders, refrigerators, air conditioners, etc. Vane etc.

  Carburizing treatment is performed so that the surface of the disk substrate 2 made of JIS SCM415 is HRC58 or higher, and finished to Ra 0.1 μm or less, and then coated with the UBMS method while introducing inert gas and hydrocarbon gas. Film formation was performed so that the content of aluminum element 3 was 0.67 at%.

Ra of the film 3 after film formation was 0.019 μm. The Young's modulus of the film 3 is 164.6.
It was GPa. In the friction test between the coating 3 and the metal ball 14, the friction coefficient is
The peeling load of 0.090 and the film 3 was 981N.

  When the coating film in this example is slid in a non-lubricated environment, the friction coefficient is 0.1 or less, and the friction coefficient is about 77% to 91% compared to steel materials without a coating film or conventional surface treatment materials. %, The coefficient of friction can be reduced by about 25% compared to the conventional film, and the peel load of the film is as large as 490 N or more, so that the low friction performance of the film can be utilized.

  When the coating in the present embodiment is applied to a non-lubricated sliding portion of a mechanical device, the load on the mechanical device involving the sliding member can be reduced, and as a result, a mechanical device with high energy efficiency can be provided. Further, the coating film of this example is compatible with sliding in a non-lubricated environment. As a result, the sliding member of a mechanical device using lubricating oil can contribute to improving the reliability of the mechanical device when the lubricating oil is depleted, while at the same time reducing the lubricating oil, resulting in the environment Can provide easy-to-use machinery.

  Carburizing treatment is performed so that the surface of the disk substrate 2 made of JIS SCM415 is HRC58 or higher, and finished to Ra 0.1 μm or less, and then coated with the UBMS method while introducing inert gas and hydrocarbon gas. Film formation was carried out so that the content of aluminum element 3 was 1.88 at%.

Ra of the film 3 after film formation was 0.021 μm. The Young's modulus of the film 3 is 158.7.
It was GPa. In the friction test between the coating 3 and the metal ball 14, the friction coefficient was 0.046, and the peeling load of the coating 3 was 588N.

  When the coating in this example is slid in a non-lubricated environment, the coefficient of friction is 0.1 or less, and the coefficient of friction is about 88% to 96% compared to steel materials without coating or conventional surface treatment materials. %, The coefficient of friction can be reduced by about 62% compared to the conventional film, and the peel load of the film is as large as 490 N or more, so that the low friction performance of the film can be utilized.

  When the coating in the present embodiment is applied to a non-lubricated sliding portion of a mechanical device, the load on the mechanical device involving the sliding member can be reduced, and as a result, a mechanical device with high energy efficiency can be provided. Further, the coating film of this example is compatible with sliding in a non-lubricated environment. As a result, the sliding member of a mechanical device using lubricating oil can contribute to improving the reliability of the mechanical device when the lubricating oil is depleted, while at the same time reducing the lubricating oil, resulting in the environment Can provide easy-to-use machinery.

  In addition, carburizing treatment is performed so that the crown surface 23 of the cam lifter 22 for an automobile made of an alloy containing Fe, Cr, Mo (chromium molybdenum steel, JIS SCM415) is equal to or higher than HRC58, and Ra is set to 0.1 μm or less. After finishing, the coating film of this example was applied to the crown surface 23 of the lifter 22 by the UBMS method while introducing an inert gas and a hydrocarbon gas. As the coating was evaluated, friction torque measurement and durability test were performed while rotating the cam 24 and sliding the cam 24 and the crown surface 23 of the lifter 22 in an oil lubrication environment. The evaluation of the coating was performed using a simulation test apparatus 21 as shown in FIG. As test conditions, SAE standard: 5W-30 engine oil 25 was dropped on the cam 24, the cam 24 was rotated at 300 r / m, and the torque applied to the camshaft 2 hours after the start of the test was measured. After this test, the presence or absence of peeling of the film was confirmed.

  As a result of the evaluation, the torque value was reduced by about 47% from a general torque value in a lifter made of JIS SCM415 without a coating. Further, peeling of the coating on the crown surface 23 was not confirmed.

  When the coating in the present embodiment is applied to the automobile cam lifter 22, the torque value decreases, so that the sliding load with the cam 24 can be reduced. Moreover, since peeling of the film does not occur, the low friction performance of the film can be continuously utilized. As a result, an automobile with high energy efficiency can be provided over a long period of time.

  Carburizing treatment is performed so that the surface of the disk substrate 2 made of JIS SCM415 is HRC58 or higher, and finished to Ra 0.1 μm or less, and then coated with the UBMS method while introducing inert gas and hydrocarbon gas. Film formation was performed so that the content of aluminum element 3 was 4.14 at%.

Ra of the film 3 after film formation was 0.020 μm. The Young's modulus of the film 3 is 80.63.
It was GPa. In the friction test between the coating 3 and the metal ball 14, the friction coefficient was 0.093, and the peeling load of the coating 3 was 1079N.

  When the coating film in this example is slid in a non-lubricated environment, the friction coefficient is 0.1 or less, and the friction coefficient is about 77% to 91% compared to steel materials without a coating film or conventional surface treatment materials. %, The coefficient of friction can be reduced by about 22% compared to the conventional film, and the peeling load of the film is as large as 490 N or more, so that the low friction performance of the film can be utilized.

  When the coating in the present embodiment is applied to a non-lubricated sliding portion of a mechanical device, the load on the mechanical device involving the sliding member can be reduced, and as a result, a mechanical device with high energy efficiency can be provided. Further, the coating film of this example is compatible with sliding in a non-lubricated environment. Therefore, in the sliding members of machinery that uses lubricating oil, it is possible to contribute to improving the reliability of the machinery when the lubricating oil is depleted, while reducing the lubricating oil, resulting in the environment Can provide easy-to-use machinery.

[Comparative Example 1]
Carburizing treatment was performed so that the surface of the disk substrate 2 made of JIS SCM415 was HRC58 or more, and finishing was performed to Ra 0.1 μm or less. A hard carbon film was not formed on the substrate 2.

  Ra of the base material 2 was 0.015 μm. The Young's modulus of the substrate 2 was 323.8 GPa. In the friction test between the base material 2 and the metal ball 14, the friction coefficient was 0.516, and the seizure load of the base material 2 was 98N.

  When the base material without a film in this comparative example is slid in an unlubricated environment, the friction coefficient cannot be reduced because the steel material without a film slides. Therefore, it is not possible to reduce the load on the mechanical device related to the sliding member, and as a result, it is not possible to provide a mechanical device with high energy efficiency. In addition, the sliding members of machinery that use lubricating oil cannot contribute to improving the reliability of machinery when the lubricating oil is depleted, and it is not possible to reduce the lubricating oil. It is not possible to provide an easy-to-use mechanical device.

[Comparative Example 2]
Carburizing treatment is performed so that the surface of the disk substrate 2 made of JIS SCM415 is HRC58 or higher, and finished to Ra 0.1 μm or less, and then coated with the UBMS method while introducing inert gas and hydrocarbon gas. Film formation was performed so that the content of aluminum element 3 was 0.10 at%.

Ra of the film 3 after film formation was 0.019 μm. The Young's modulus of the film 3 is 74.13.
It was GPa. Further, in the friction test between the coating 3 and the metal ball 14, the friction coefficient was 0.133, and the peeling load of the coating 3 was 2452N or more.

  When the film in this comparative example is slid in an unlubricated environment, the film 3 is excellent in peel resistance, but the friction coefficient cannot be reduced as compared with the conventional film. Therefore, it is not possible to provide an environmentally friendly mechanical device at the sliding portion of the mechanical device using the lubricating oil.

  In addition, carburizing treatment is performed so that the crown surface 23 of the cam lifter 22 for an automobile made of an alloy containing Fe, Cr, Mo (chromium molybdenum steel, JIS SCM415) is equal to or higher than HRC58, and Ra is set to 0.1 μm or less. After finishing, the coating of this comparative example was applied to the crown surface 23 of the valve lifter 22 by the UBMS method while introducing an inert gas and a hydrocarbon gas. The evaluation of the coating is the same as in Example 3.

  As a result of the evaluation, the torque value was reduced by about 43% from a general torque value in a lifter made of JIS SCM415 without a coating. However, partial peeling was confirmed in the coating on the crown surface 23.

  When the coating in this comparative example is applied to the automobile cam lifter 22, the torque value is reduced, so that the sliding load with the cam 24 can be reduced. However, since the coating partly peels off, the low friction performance of the coating cannot be utilized continuously. As a result, it is not possible to provide a car with high energy efficiency over a long period of time.

[Comparative Example 3]
Carburizing treatment is performed so that the surface of the disk substrate 2 made of JIS SCM415 is HRC58 or higher, and finished to Ra 0.1 μm or less, and then coated with the UBMS method while introducing inert gas and hydrocarbon gas. Film formation was carried out so that the content of aluminum element 3 was 5.94 at%.

Ra of the film 3 after film formation was 0.021 μm. The Young's modulus of the coating 3 is 193.0
It was GPa. In the friction test between the coating 3 and the metal ball 14, the friction coefficient was 0.602, and the peeling load of the coating 3 was 98N.

  When the hard carbon film in this comparative example is slid in a non-lubricated environment, the friction coefficient cannot be reduced as compared with steel materials without a film or conventional surface treatment materials. Therefore, it is not possible to reduce the load on the mechanical device related to the sliding member, and as a result, it is not possible to provide a mechanical device with high energy efficiency. In addition, since the coating of this comparative example does not support sliding in a non-lubricated environment, the reliability as a mechanical device when the lubricating oil is depleted in the sliding portion of the mechanical device using the lubricating oil Since it cannot contribute to improvement and cannot reduce the lubricating oil, it cannot provide an environmentally friendly mechanical device.

[Comparative Example 4]
Carburizing treatment is performed so that the surface of the disk substrate 2 made of JIS SCM415 becomes HRC58 or more, and finished to Ra 0.1 μm or less, and then coated by UBMS method while introducing inert gas and hydrocarbon gas. Film formation was performed so that the content of aluminum element 3 was 11.52 at%.

Ra of the film 3 after film formation was 0.019 μm. The Young's modulus of the film 3 is 80.90.
It was GPa. In the friction test between the coating 3 and the metal ball 14, the friction coefficient was 0.080, and the peeling load of the coating 3 was 392N.

  When the hard carbon film in this comparative example is slid in an unlubricated environment, the peel resistance is inferior but the friction coefficient is low. Although effective in sliding in a low load region, it is not necessarily effective in sliding in a high load region.

  That is, it is difficult to reduce the load on the mechanical device involving the sliding member, and as a result, it is difficult to provide a mechanical device with high energy efficiency. In addition, since the effect of reducing the lubricating oil is small, it is not possible to provide an environmentally friendly mechanical device.

  The present invention relates to a hard carbon coating that can be applied to a sliding member used in a non-lubricated environment and in a water, organic solvent, fuel, and oil lubricated environment.

It is an isometric view explanatory drawing of the test piece which formed the hard carbon film on the disc base material. It is sectional explanatory drawing of the friction tester used for evaluation of this invention. It is a perspective explanatory view of a friction testing machine (test piece-ball sliding part) used for evaluation of the present invention. It is a figure which shows the simulation test apparatus of the cam lifter for motor vehicles.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Test piece, 2 ... Disk base material, 3 ... Hard carbon coating, 11 ... Abrasion tester, 12 ... Rotating shaft,
DESCRIPTION OF SYMBOLS 13 ... Work table, 14 ... Metal ball, 15 ... Spring, 16 ... Holder, 17 ... Motor, 18 ... Load cell, 21 ... Simulation test device, 22 ... Automotive cam lifter, 23 ... Crown, 24 ... Cam, 25 ... Engine oil.

Claims (7)

On the substrate, a hard carbon film composed of a diamond-like carbon film containing an aluminum element of 0.5 at% or more and 4.5 at% or less is formed by an unbalanced magnetron sputtering (UBMS) method,
A method for producing a sliding member, wherein an aluminum element exposed on the surface of the hard carbon film is reacted with oxygen or water in the atmosphere to form aluminum oxide and / or aluminum hydroxide.   The sliding member obtained by the manufacturing method according to claim 1, wherein the Young's modulus of the hard carbon film formed on the substrate is 50 GPa or more and 180 GPa or less.   The sliding member according to claim 2, wherein the thickness of the hard carbon coating is 0.5 µm or more and 10.0 µm or less, and the surface roughness of the hard carbon coating is 0.1 µm or less. 4. The sliding member according to claim 2, wherein the hard carbon film contains sp ² bonded carbon and sp ³ bonded carbon. The sliding member according to any one of claims 2 to 4, wherein the base material is made of an alloy containing Fe, Cr, and Mo.   6. The sliding member according to claim 5, wherein a Cr layer is formed on the alloy containing Fe, Cr, and Mo.   7. The sliding member according to claim 6, wherein a Cr / C layer in which Cr and C are mixed is formed on the Cr layer.

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